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Jump start kils ECU
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Chris Whelan
Mar 28, 2013, 9:30:31 AM3/28/13
to
For all the nay-sayers here that deny jump-starting incorrectly cannot
spike an ECU, the following may be of interest.
A neighbour recently bought a '53 plate 206SW (diesel) as a runabout.
He's an experienced DIYer; he's currently doing a shell-up rebuild on a
Moggy.
When he collected the car, the fuel light was on. He got home, but the
next day it wouldn't start. He tipped 10 litres in, and had the usual
problems bleeding it. Eventually it started. By then the battery was
almost flat.
The next day, the battery was too flat to crank it. He jumped it off a
mate's car, without taking any precautions. It failed to start, and he
then began a long series of investigations to try to fix it.
Eventually, he came to the conclusion that there was only the ECU left.
He sent it away to an independent repairer who diagnosed it as faulty,
and repaired it. The repairer told him that ECU's fried after jump-
starting were so common, it was the first question he asked when someone
phoned him for advice.
With the repaired ECU in place, it fired up and ran straight away...
Chris
--
Remove prejudice to reply.
--
Remove prejudice to reply.
spike an ECU, the following may be of interest.
A neighbour recently bought a '53 plate 206SW (diesel) as a runabout.
He's an experienced DIYer; he's currently doing a shell-up rebuild on a
Moggy.
When he collected the car, the fuel light was on. He got home, but the
next day it wouldn't start. He tipped 10 litres in, and had the usual
problems bleeding it. Eventually it started. By then the battery was
almost flat.
The next day, the battery was too flat to crank it. He jumped it off a
mate's car, without taking any precautions. It failed to start, and he
then began a long series of investigations to try to fix it.
Eventually, he came to the conclusion that there was only the ECU left.
He sent it away to an independent repairer who diagnosed it as faulty,
and repaired it. The repairer told him that ECU's fried after jump-
starting were so common, it was the first question he asked when someone
phoned him for advice.
With the repaired ECU in place, it fired up and ran straight away...
Chris
--
Remove prejudice to reply.
--
Remove prejudice to reply.
Dave Plowman (News)
Mar 28, 2013, 10:05:00 AM3/28/13
to
Sounds like a make to avoid, then, with such badly designed electronics.
--
*How's my driving? Call 999*
Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.
--
*How's my driving? Call 999*
Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.
Duncan Wood
Mar 28, 2013, 10:46:17 AM3/28/13
to
On Thu, 28 Mar 2013 14:05:00 -0000, Dave Plowman (News)
<da...@davenoise.co.uk> wrote:
> Sounds like a make to avoid, then, with such badly designed electronics.
>
Applies to all makes without a load dump suppressor. Switching the
<da...@davenoise.co.uk> wrote:
> Sounds like a make to avoid, then, with such badly designed electronics.
>
headlamps & rear demister on before disconnecting the jump leads avoids
most of it.
Chris Whelan
Mar 28, 2013, 10:59:35 AM3/28/13
to
On Thu, 28 Mar 2013 14:05:00 +0000, Dave Plowman (News) wrote:
> Sounds like a make to avoid, then, with such badly designed electronics.
Not really; last vehicle I had direct experience of in this regard was a
> Sounds like a make to avoid, then, with such badly designed electronics.
VW.
TMack
Mar 28, 2013, 11:29:09 AM3/28/13
to
On Thu, 28 Mar 2013 13:30:31 +0000, Chris Whelan wrote:
> The repairer told him that ECU's fried after jump-
> starting were so common, it was the first question he asked when someone
> phoned him for advice.
This is a classic case of a correlation NOT providing proof of a causal
> The repairer told him that ECU's fried after jump-
> starting were so common, it was the first question he asked when someone
> phoned him for advice.
relationship. For example - many people whose vehicles won't start will
keep trying until the battery is too flat to turn the engine. The next
thing they try is a jump start... An ECU fault may have been the reason
for the original non-starting - but it is subsequently interpreted as
having been *caused* by the attempts to jump start.
It is possible that jump starts are the major cause of ECU failure but it
would take more than an anecdotal account of a correlation to provide good
evidence for the causal relationship.
--
Tony
'09 FJR1300, '04 Ducati ST3, '87 TW200,
'94 PC800, OMF#24
Chris Whelan
Mar 28, 2013, 11:58:10 AM3/28/13
to
On Thu, 28 Mar 2013 15:29:09 +0000, TMack wrote:
> On Thu, 28 Mar 2013 13:30:31 +0000, Chris Whelan wrote:
>> The repairer told him that ECU's fried after jump-
>> starting were so common, it was the first question he asked when
>> someone phoned him for advice.
>
> This is a classic case of a correlation NOT providing proof of a causal
> relationship. For example - many people whose vehicles won't start will
> keep trying until the battery is too flat to turn the engine. The next
> thing they try is a jump start... An ECU fault may have been the reason
> for the original non-starting - but it is subsequently interpreted as
> having been *caused* by the attempts to jump start.
But in this case, it would be a huge coincidence that the non-start was
> On Thu, 28 Mar 2013 13:30:31 +0000, Chris Whelan wrote:
>> The repairer told him that ECU's fried after jump-
>> starting were so common, it was the first question he asked when
>> someone phoned him for advice.
>
> This is a classic case of a correlation NOT providing proof of a causal
> relationship. For example - many people whose vehicles won't start will
> keep trying until the battery is too flat to turn the engine. The next
> thing they try is a jump start... An ECU fault may have been the reason
> for the original non-starting - but it is subsequently interpreted as
> having been *caused* by the attempts to jump start.
caused by ECU failure; the battery was clearly flat before the non-start
condition.
In the other case that I have knowledge of, the vehicle was left for a
number of weeks, and the battery was too flat to start it also, so there
was a reason other than ECU failure for the non-start.
> It is possible that jump starts are the major cause of ECU failure but
> it would take more than an anecdotal account of a correlation to provide
> good evidence for the causal relationship.
commercial operation, after all. They invested heavily a number of years
ago in devices to prevent spiking ECU's when jump-starting, and patrols
were threatened with disciplinary action if they failed to use them.
Dave Plowman (News)
Mar 28, 2013, 3:26:52 PM3/28/13
to
In article <op.wunvbfg9loxewg@duncan-tosh>,
--
*Never put off until tomorrow what you can avoid altogether *
Duncan Wood <nnt...@dmx512.co.uk> wrote:
> > Sounds like a make to avoid, then, with such badly designed
> > electronics.
> >
> Applies to all makes without a load dump suppressor. Switching the
> headlamps & rear demister on before disconnecting the jump leads avoids
> most of it.
Load dump suppressor? Is that a polite name for a voltage regulator?
> > Sounds like a make to avoid, then, with such badly designed
> > electronics.
> >
> Applies to all makes without a load dump suppressor. Switching the
> headlamps & rear demister on before disconnecting the jump leads avoids
> most of it.
--
*Never put off until tomorrow what you can avoid altogether *
TMack
Mar 28, 2013, 3:51:44 PM3/28/13
to
On Thu, 28 Mar 2013 15:58:10 +0000, Chris Whelan wrote:
> On Thu, 28 Mar 2013 15:29:09 +0000, TMack wrote:
>
>> On Thu, 28 Mar 2013 13:30:31 +0000, Chris Whelan wrote:
>>> The repairer told him that ECU's fried after jump-
>>> starting were so common, it was the first question he asked when
>>> someone phoned him for advice.
>>
>> This is a classic case of a correlation NOT providing proof of a causal
>> relationship. For example - many people whose vehicles won't start will
>> keep trying until the battery is too flat to turn the engine. The next
>> thing they try is a jump start... An ECU fault may have been the
>> reason for the original non-starting - but it is subsequently
>> interpreted as having been *caused* by the attempts to jump start.
>
> But in this case, it would be a huge coincidence that the non-start was
> caused by ECU failure; the battery was clearly flat before the non-start
> condition.
I didn't express a view about whether or not this particular case might
> On Thu, 28 Mar 2013 15:29:09 +0000, TMack wrote:
>
>> On Thu, 28 Mar 2013 13:30:31 +0000, Chris Whelan wrote:
>>> The repairer told him that ECU's fried after jump-
>>> starting were so common, it was the first question he asked when
>>> someone phoned him for advice.
>>
>> This is a classic case of a correlation NOT providing proof of a causal
>> relationship. For example - many people whose vehicles won't start will
>> keep trying until the battery is too flat to turn the engine. The next
>> thing they try is a jump start... An ECU fault may have been the
>> reason for the original non-starting - but it is subsequently
>> interpreted as having been *caused* by the attempts to jump start.
>
> But in this case, it would be a huge coincidence that the non-start was
> caused by ECU failure; the battery was clearly flat before the non-start
> condition.
have been related to jump starting. However, the flat battery might, for
example, have been due to a loose battery terminal with intermittent
disconnects or a defect in the battery itself, either of which can also
cause voltage spikes and ECU damage in an unprotected ECU.
> In the other case that I have knowledge of, the vehicle was left for a
> number of weeks, and the battery was too flat to start it also, so there
> was a reason other than ECU failure for the non-start.
possible dodgy batteries or connections. Hardly the basis for a
generalisation.
>> It is possible that jump starts are the major cause of ECU failure but
>> it would take more than an anecdotal account of a correlation to
>> provide good evidence for the causal relationship.
>
> The AA are not noted for spending money unnecessarily; they are a
> commercial operation, after all. They invested heavily a number of years
> ago in devices to prevent spiking ECU's when jump-starting, and patrols
> were threatened with disciplinary action if they failed to use them.
*never* cause an ECU fault. I simply disputed that the *evidence
presented* was sufficient to support the view that jump starts are the
main cause of ECU failure. It might be true but one would need better
evidence before coming to that conclusion.
steve robinson
Mar 28, 2013, 4:02:30 PM3/28/13
to
Chris Whelan wrote:
> On Thu, 28 Mar 2013 15:29:09 +0000, TMack wrote:
>
> > On Thu, 28 Mar 2013 13:30:31 +0000, Chris Whelan wrote:
> >> The repairer told him that ECU's fried after jump-
> >> starting were so common, it was the first question he asked when
> >> someone phoned him for advice.
> >
> > This is a classic case of a correlation NOT providing proof of a
> > causal relationship. For example - many people whose vehicles won't
> > start will keep trying until the battery is too flat to turn the
> > engine. The next thing they try is a jump start... An ECU fault
> > may have been the reason for the original non-starting - but it is
> > subsequently interpreted as having been caused by the attempts to
> On Thu, 28 Mar 2013 15:29:09 +0000, TMack wrote:
>
> > On Thu, 28 Mar 2013 13:30:31 +0000, Chris Whelan wrote:
> >> The repairer told him that ECU's fried after jump-
> >> starting were so common, it was the first question he asked when
> >> someone phoned him for advice.
> >
> > This is a classic case of a correlation NOT providing proof of a
> > causal relationship. For example - many people whose vehicles won't
> > start will keep trying until the battery is too flat to turn the
> > engine. The next thing they try is a jump start... An ECU fault
> > may have been the reason for the original non-starting - but it is
> > jump start.
>
> But in this case, it would be a huge coincidence that the non-start
> was caused by ECU failure; the battery was clearly flat before the
> non-start condition.
>
> In the other case that I have knowledge of, the vehicle was left for
> a number of weeks, and the battery was too flat to start it also, so
> there was a reason other than ECU failure for the non-start.
>
> > It is possible that jump starts are the major cause of ECU failure
> > but it would take more than an anecdotal account of a correlation
> > to provide good evidence for the causal relationship.
>
> The AA are not noted for spending money unnecessarily; they are a
> commercial operation, after all. They invested heavily a number of
> years ago in devices to prevent spiking ECU's when jump-starting, and
> patrols were threatened with disciplinary action if they failed to
> use them.
>
> Chris
Most people dont have a clue how to jump start a vehicle correctly
>
> But in this case, it would be a huge coincidence that the non-start
> was caused by ECU failure; the battery was clearly flat before the
> non-start condition.
>
> In the other case that I have knowledge of, the vehicle was left for
> a number of weeks, and the battery was too flat to start it also, so
> there was a reason other than ECU failure for the non-start.
>
> > It is possible that jump starts are the major cause of ECU failure
> > but it would take more than an anecdotal account of a correlation
> > to provide good evidence for the causal relationship.
>
> The AA are not noted for spending money unnecessarily; they are a
> commercial operation, after all. They invested heavily a number of
> years ago in devices to prevent spiking ECU's when jump-starting, and
> patrols were threatened with disciplinary action if they failed to
> use them.
>
> Chris
anyway.
you should never connect the earth (usally negative) directly to the
battery
If they provide jump start points use them
When you have connected the cables up correcttly allow the donor
vehicle to run for approx 10 minutes to partially charge the dead
vehicles battery
Duncan Wood
Mar 28, 2013, 4:19:15 PM3/28/13
to
On Thu, 28 Mar 2013 19:26:52 -0000, Dave Plowman (News)
<da...@davenoise.co.uk> wrote:
> In article <op.wunvbfg9loxewg@duncan-tosh>,
> Duncan Wood <nnt...@dmx512.co.uk> wrote:
>> > Sounds like a make to avoid, then, with such badly designed
>> > electronics.
>> >
>
>> Applies to all makes without a load dump suppressor. Switching the
>> headlamps & rear demister on before disconnecting the jump leads avoids
>> most of it.
>
> Load dump suppressor? Is that a polite name for a voltage regulator?
>
No, the voltage reg controls the field coils, the suppressor either
<da...@davenoise.co.uk> wrote:
> In article <op.wunvbfg9loxewg@duncan-tosh>,
> Duncan Wood <nnt...@dmx512.co.uk> wrote:
>> > Sounds like a make to avoid, then, with such badly designed
>> > electronics.
>> >
>
>> Applies to all makes without a load dump suppressor. Switching the
>> headlamps & rear demister on before disconnecting the jump leads avoids
>> most of it.
>
> Load dump suppressor? Is that a polite name for a voltage regulator?
>
directly trys to clamp the peak voltage or just crowbars the output.
Chris Whelan
Mar 28, 2013, 5:36:49 PM3/28/13
to
On Thu, 28 [...]
> I didn't express a view about whether or not this particular case might
> have been related to jump starting. However, the flat battery might,
> for example, have been due to a loose battery terminal with intermittent
> disconnects or a defect in the battery itself, either of which can also
> cause voltage spikes and ECU damage in an unprotected ECU.
As I explained, in the first case the battery was flat having been used
to bleed through a diesel that had run out of fuel, and in the second
case it was a vehicle that had been unused for a number of weeks.
> So that's a sample size of 2 from your experience. Both vehicles with
> possible dodgy batteries or connections. Hardly the basis for a
> generalisation.
No dodgy batteries/ connections. (See above.)
[...]
> The AA example proves nothing.
Why not? Why would they invest in extra equipment and training if they
hadn't seen spiked ECU's caused by wrong jump-starting? I'm not trying to
*prove* anything BTW; just perhaps save someone some unnecessary expense.
> I didn't say that a jump start could
> *never* cause an ECU fault.
Re-read my original post; It's addressed 'To the nay-sayers...'
There are some regulars who post here who in the past *have* said that
jump-starting cannot spike an ECU.
> I simply disputed that the *evidence
> presented* was sufficient to support the view that jump starts are the
> main cause of ECU failure. It might be true but one would need better
> evidence before coming to that conclusion.
I never said that jump-starts are the *main* cause of ECU failure; I said
that the company that repairs them finds that it's a common reason for
such failures.
> I didn't express a view about whether or not this particular case might
> have been related to jump starting. However, the flat battery might,
> for example, have been due to a loose battery terminal with intermittent
> disconnects or a defect in the battery itself, either of which can also
> cause voltage spikes and ECU damage in an unprotected ECU.
to bleed through a diesel that had run out of fuel, and in the second
case it was a vehicle that had been unused for a number of weeks.
> So that's a sample size of 2 from your experience. Both vehicles with
> possible dodgy batteries or connections. Hardly the basis for a
> generalisation.
[...]
> The AA example proves nothing.
hadn't seen spiked ECU's caused by wrong jump-starting? I'm not trying to
*prove* anything BTW; just perhaps save someone some unnecessary expense.
> I didn't say that a jump start could
> *never* cause an ECU fault.
There are some regulars who post here who in the past *have* said that
jump-starting cannot spike an ECU.
> I simply disputed that the *evidence
> presented* was sufficient to support the view that jump starts are the
> main cause of ECU failure. It might be true but one would need better
> evidence before coming to that conclusion.
that the company that repairs them finds that it's a common reason for
such failures.
Dave Plowman (News)
Mar 28, 2013, 7:42:47 PM3/28/13
to
In article <op.wuoaqdgiloxewg@duncan-tosh>,
should be perfectly capable of handling any spikes - even although I'm
not convinced they occur. If it can't, it's badly designed. And how come
it's always the ECU that suffers - not any of the other electronic
equipment on the car? How come they seem to be designed to cope with these
'spikes' or whatever - but the most essential bit, the ECU - can't?
--
*A backward poet writes inverse.*
Duncan Wood <nnt...@dmx512.co.uk> wrote:
> >> Applies to all makes without a load dump suppressor. Switching the
> >> headlamps & rear demister on before disconnecting the jump leads avoids
> >> most of it.
> >
> > Load dump suppressor? Is that a polite name for a voltage regulator?
> >
> No, the voltage reg controls the field coils, the suppressor either
> directly trys to clamp the peak voltage or just crowbars the output.
I'm talking about the voltage regulator in the ECU. The design of that
> >> Applies to all makes without a load dump suppressor. Switching the
> >> headlamps & rear demister on before disconnecting the jump leads avoids
> >> most of it.
> >
> > Load dump suppressor? Is that a polite name for a voltage regulator?
> >
> No, the voltage reg controls the field coils, the suppressor either
> directly trys to clamp the peak voltage or just crowbars the output.
should be perfectly capable of handling any spikes - even although I'm
not convinced they occur. If it can't, it's badly designed. And how come
it's always the ECU that suffers - not any of the other electronic
equipment on the car? How come they seem to be designed to cope with these
'spikes' or whatever - but the most essential bit, the ECU - can't?
--
*A backward poet writes inverse.*
Duncan Wood
Mar 28, 2013, 8:21:26 PM3/28/13
to
On Thu, 28 Mar 2013 23:42:47 -0000, Dave Plowman (News)
<da...@davenoise.co.uk> wrote:
> In article <op.wuoaqdgiloxewg@duncan-tosh>,
> Duncan Wood <nnt...@dmx512.co.uk> wrote:
>> >> Applies to all makes without a load dump suppressor. Switching the
>> >> headlamps & rear demister on before disconnecting the jump leads
>> avoids
>> >> most of it.
>> >
>> > Load dump suppressor? Is that a polite name for a voltage regulator?
>> >
>
>> No, the voltage reg controls the field coils, the suppressor either
>> directly trys to clamp the peak voltage or just crowbars the output.
>
> I'm talking about the voltage regulator in the ECU. The design of that
> should be perfectly capable of handling any spikes - even although I'm
> not convinced they occur. If it can't, it's badly designed.
In that case they're all badly designed, they all regulate the field
<da...@davenoise.co.uk> wrote:
> In article <op.wuoaqdgiloxewg@duncan-tosh>,
> Duncan Wood <nnt...@dmx512.co.uk> wrote:
>> >> Applies to all makes without a load dump suppressor. Switching the
>> >> headlamps & rear demister on before disconnecting the jump leads
>> avoids
>> >> most of it.
>> >
>> > Load dump suppressor? Is that a polite name for a voltage regulator?
>> >
>
>> No, the voltage reg controls the field coils, the suppressor either
>> directly trys to clamp the peak voltage or just crowbars the output.
>
> I'm talking about the voltage regulator in the ECU. The design of that
> should be perfectly capable of handling any spikes - even although I'm
> not convinced they occur. If it can't, it's badly designed.
current. Look up load dump, Bosch have published quite a lot on them,
there's a whole set of standardswritten
> And how come
> it's always the ECU that suffers - not any of the other electronic
> equipment on the car?
Arfa Daily
Mar 28, 2013, 9:26:11 PM3/28/13
to
"steve robinson" <st...@colevalleyinteriors.co.uk> wrote in message
news:xn0ig49c...@reader80.eternal-september.org...
always been told that the ground side of the battery was *exactly* the place
to connect to, with the positive side directly on the "+" terminal, because
this was the lowest impedance point in the entire electrical system, where
the voltage will do its utmost to stay at the nominal terminal voltage of
that battery ie the battery will try to 'slug' any unwanted spikes. I was
also always taught that once the target vehicle had started, the donor
vehicle should be disconnected as soon as possible to avoid having two
alternators - which, with the best will in the world will not have the same
exact output voltage if for no other reason than that one is on a the end of
a fully charged battery, and the other isn't - fighting one another. The
target vehicle's own alternator should have plenty enough capacity on its
own to charge a battery from flat to a useable condition at least, in 10
minutes of running. I accept, however, that this wasn't the case in days of
yore when dynamos and mechanical regulators were the norm.
Maybe it's all different now, but I have jump started plenty of vehicles
over the years that have ECUs, and using the 'rules' that I was taught, and
have never had an issue. I have to say that being an electronics service
person of many years experience myself, I am surprised that an ECU could be
so readily damaged. Car electronics of any description - and particularly
anything under the bonnet - have to cope with some of the most hostile
conditions that could possibly be thrown at them, and that includes oceans
of electrical noise and spikes, and I'm sure that the designers would
incorporate the necessary protections into their circuitry to allow it to
cope.
Anyway, all that aside, I like the idea of having the headlights or some
other large load switched on before disconnecting the donor vehicle. I can
see how this may well have a 'swamping' effect on the electrical system,
mitigating any potential high voltage spikes when the disconnection takes
place. I shall add that 'tip' to my store of things to remember ... :-)
Arfa
Chris Whelan
Mar 29, 2013, 3:26:52 AM3/29/13
to
On Fri, 29 Mar 2013 01:26:11 +0000, Arfa Daily wrote:
[...]
> Hmmm. That all runs contrary to what I had been lead to believe. I had
> always been told that the ground side of the battery was *exactly* the
> place to connect to,
The problem is that when you make the last connection the two systems are
at different voltages, so a spark may occur. It's likely that both
batteries are gassing, so there's a *very* small chance of an explosion.
Standard advice is to make the final earth connection directly to a point
on the engine block, and as far from the battery as possible.
> with the positive side directly on the "+"
> terminal, because this was the lowest impedance point in the entire
> electrical system, where the voltage will do its utmost to stay at the
> nominal terminal voltage of that battery ie the battery will try to
> 'slug' any unwanted spikes. I was also always taught that once the
> target vehicle had started, the donor vehicle should be disconnected as
> soon as possible to avoid having two alternators - which, with the best
> will in the world will not have the same exact output voltage if for no
> other reason than that one is on a the end of a fully charged battery,
> and the other isn't - fighting one another.
I understand your thinking, but in practice leaving them connected for a
while seems to cause no problem. It's disconnecting under the situation
that the two batteries have greatly different states of charge that cause
the problem. Leaving them connected and running mitigates that to some
degree.
> The target vehicle's own
> alternator should have plenty enough capacity on its own to charge a
> battery from flat to a useable condition at least, in 10 minutes of
> running. I accept, however, that this wasn't the case in days of yore
> when dynamos and mechanical regulators were the norm.
A completely flat battery would usually need more than 10 minutes of
running at tickover in order to have sufficient charge to restart the
vehicle. Even twice that time might be insufficient.
> Maybe it's all different now, but I have jump started plenty of vehicles
> over the years that have ECUs, and using the 'rules' that I was taught,
> and have never had an issue.
I doubt that you've jump-started as many vehicles as the motoring
organisations do in a year, and they deem the problem to be of sufficient
magnitude to make it worth while taking precautions.
> I have to say that being an electronics
> service person of many years experience myself, I am surprised that an
> ECU could be so readily damaged. Car electronics of any description -
> and particularly anything under the bonnet - have to cope with some of
> the most hostile conditions that could possibly be thrown at them, and
> that includes oceans of electrical noise and spikes, and I'm sure that
> the designers would incorporate the necessary protections into their
> circuitry to allow it to cope.
Bear in mind the key factor in mass-market car design is cost; if a
designer can save a few pounds on every car, even at the expense of some
reduction in service life or reliability, (s)he would be hailed as a hero!
> Anyway, all that aside, I like the idea of having the headlights or some
> other large load switched on before disconnecting the donor vehicle. I
> can see how this may well have a 'swamping' effect on the electrical
> system, mitigating any potential high voltage spikes when the
> disconnection takes place. I shall add that 'tip' to my store of things
> to remember ... :-)
[...]
> Hmmm. That all runs contrary to what I had been lead to believe. I had
> always been told that the ground side of the battery was *exactly* the
> place to connect to,
at different voltages, so a spark may occur. It's likely that both
batteries are gassing, so there's a *very* small chance of an explosion.
Standard advice is to make the final earth connection directly to a point
on the engine block, and as far from the battery as possible.
> with the positive side directly on the "+"
> terminal, because this was the lowest impedance point in the entire
> electrical system, where the voltage will do its utmost to stay at the
> nominal terminal voltage of that battery ie the battery will try to
> 'slug' any unwanted spikes. I was also always taught that once the
> target vehicle had started, the donor vehicle should be disconnected as
> soon as possible to avoid having two alternators - which, with the best
> will in the world will not have the same exact output voltage if for no
> other reason than that one is on a the end of a fully charged battery,
> and the other isn't - fighting one another.
while seems to cause no problem. It's disconnecting under the situation
that the two batteries have greatly different states of charge that cause
the problem. Leaving them connected and running mitigates that to some
degree.
> The target vehicle's own
> alternator should have plenty enough capacity on its own to charge a
> battery from flat to a useable condition at least, in 10 minutes of
> running. I accept, however, that this wasn't the case in days of yore
> when dynamos and mechanical regulators were the norm.
running at tickover in order to have sufficient charge to restart the
vehicle. Even twice that time might be insufficient.
> Maybe it's all different now, but I have jump started plenty of vehicles
> over the years that have ECUs, and using the 'rules' that I was taught,
> and have never had an issue.
organisations do in a year, and they deem the problem to be of sufficient
magnitude to make it worth while taking precautions.
> I have to say that being an electronics
> service person of many years experience myself, I am surprised that an
> ECU could be so readily damaged. Car electronics of any description -
> and particularly anything under the bonnet - have to cope with some of
> the most hostile conditions that could possibly be thrown at them, and
> that includes oceans of electrical noise and spikes, and I'm sure that
> the designers would incorporate the necessary protections into their
> circuitry to allow it to cope.
designer can save a few pounds on every car, even at the expense of some
reduction in service life or reliability, (s)he would be hailed as a hero!
> Anyway, all that aside, I like the idea of having the headlights or some
> other large load switched on before disconnecting the donor vehicle. I
> can see how this may well have a 'swamping' effect on the electrical
> system, mitigating any potential high voltage spikes when the
> disconnection takes place. I shall add that 'tip' to my store of things
> to remember ... :-)
Dave Plowman (News)
Mar 29, 2013, 7:08:08 AM3/29/13
to
In article <op.wuolx...@duncan-tosh.cable.virginmedia.net>,
engine management system? I find that very hard to believe. I know it is
done with some. But in any case it makes no difference - a well designed
one would provide protection on that input. After all, jump starting isn't
exactly uncommon.
> > And how come
> > it's always the ECU that suffers - not any of the other electronic
> > equipment on the car?
> Nobody else has suggested they don't affect other things.
> > How come they seem to be designed to cope with these
> > 'spikes' or whatever - but the most essential bit, the ECU - can't?
--
*We never really grow up, we only learn how to act in public.
Duncan Wood <nnt...@dmx512.co.uk> wrote:
> >> > Load dump suppressor? Is that a polite name for a voltage regulator?
> >> >
> >
> >> No, the voltage reg controls the field coils, the suppressor either
> >> directly trys to clamp the peak voltage or just crowbars the output.
> >
> > I'm talking about the voltage regulator in the ECU. The design of that
> > should be perfectly capable of handling any spikes - even although I'm
> > not convinced they occur. If it can't, it's badly designed.
> In that case they're all badly designed, they all regulate the field
> current. Look up load dump, Bosch have published quite a lot on them,
> there's a whole set of standardswritten
You are saying every single new car has the alternator controlled by the
> >> > Load dump suppressor? Is that a polite name for a voltage regulator?
> >> >
> >
> >> No, the voltage reg controls the field coils, the suppressor either
> >> directly trys to clamp the peak voltage or just crowbars the output.
> >
> > I'm talking about the voltage regulator in the ECU. The design of that
> > should be perfectly capable of handling any spikes - even although I'm
> > not convinced they occur. If it can't, it's badly designed.
> In that case they're all badly designed, they all regulate the field
> current. Look up load dump, Bosch have published quite a lot on them,
> there's a whole set of standardswritten
engine management system? I find that very hard to believe. I know it is
done with some. But in any case it makes no difference - a well designed
one would provide protection on that input. After all, jump starting isn't
exactly uncommon.
> > And how come
> > it's always the ECU that suffers - not any of the other electronic
> > equipment on the car?
> Nobody else has suggested they don't affect other things.
> > How come they seem to be designed to cope with these
> > 'spikes' or whatever - but the most essential bit, the ECU - can't?
*We never really grow up, we only learn how to act in public.
Dave Plowman (News)
Mar 29, 2013, 7:18:32 AM3/29/13
to
In article <V465t.120176$gt1.1...@fx04.fr7>,
connecting directly to it? Some cars - like BMW - do have dedicated jump
start points under the bonnet - but this is just for added convenience
since the battery is in the boot.
> I was also always taught that once the target vehicle had started, the
> donor vehicle should be disconnected as soon as possible to avoid
> having two alternators - which, with the best will in the world will
> not have the same exact output voltage if for no other reason than that
> one is on a the end of a fully charged battery, and the other isn't -
> fighting one another. The target vehicle's own alternator should have
> plenty enough capacity on its own to charge a battery from flat to a
> useable condition at least, in 10 minutes of running. I accept,
> however, that this wasn't the case in days of yore when dynamos and
> mechanical regulators were the norm.
With some alternators, if a battery is totally fooked, they wont produce a
charge. And if they do and it is, may produce rather more than the nominal
12 volts. The best way is to charge the flat battery off the donor car for
a few minutes, if it has shown no signs of life. Then disconnect, and see
if the flat battery has taken a charge. if it has, proceed as normal. If
not, don't attempt a jump start.
> Maybe it's all different now, but I have jump started plenty of vehicles
> over the years that have ECUs, and using the 'rules' that I was taught,
> and have never had an issue. I have to say that being an electronics
> service person of many years experience myself, I am surprised that an
> ECU could be so readily damaged. Car electronics of any description -
> and particularly anything under the bonnet - have to cope with some of
> the most hostile conditions that could possibly be thrown at them, and
> that includes oceans of electrical noise and spikes, and I'm sure that
> the designers would incorporate the necessary protections into their
> circuitry to allow it to cope.
Other thing is just how ready some makers are to produce a snap answer to
a failure by blaming it on the user.
--
*I used up all my sick days so I called in dead
Arfa Daily <arfa....@ntlworld.com> wrote:
> > Most people dont have a clue how to jump start a vehicle correctly
> > anyway.
> >
> > you should never connect the earth (usally negative) directly to the
> > battery
> >
> > If they provide jump start points use them
> >
> > When you have connected the cables up correcttly allow the donor
> > vehicle to run for approx 10 minutes to partially charge the dead
> > vehicles battery
> >
> Hmmm. That all runs contrary to what I had been lead to believe. I had
> always been told that the ground side of the battery was *exactly* the
> place to connect to, with the positive side directly on the "+"
> terminal, because this was the lowest impedance point in the entire
> electrical system, where the voltage will do its utmost to stay at the
> nominal terminal voltage of that battery ie the battery will try to
> 'slug' any unwanted spikes.
Quite. A battery has a very low impedance so why add to this by not
> > Most people dont have a clue how to jump start a vehicle correctly
> > anyway.
> >
> > you should never connect the earth (usally negative) directly to the
> > battery
> >
> > If they provide jump start points use them
> >
> > When you have connected the cables up correcttly allow the donor
> > vehicle to run for approx 10 minutes to partially charge the dead
> > vehicles battery
> >
> Hmmm. That all runs contrary to what I had been lead to believe. I had
> always been told that the ground side of the battery was *exactly* the
> place to connect to, with the positive side directly on the "+"
> terminal, because this was the lowest impedance point in the entire
> electrical system, where the voltage will do its utmost to stay at the
> nominal terminal voltage of that battery ie the battery will try to
> 'slug' any unwanted spikes.
connecting directly to it? Some cars - like BMW - do have dedicated jump
start points under the bonnet - but this is just for added convenience
since the battery is in the boot.
> I was also always taught that once the target vehicle had started, the
> donor vehicle should be disconnected as soon as possible to avoid
> having two alternators - which, with the best will in the world will
> not have the same exact output voltage if for no other reason than that
> one is on a the end of a fully charged battery, and the other isn't -
> fighting one another. The target vehicle's own alternator should have
> plenty enough capacity on its own to charge a battery from flat to a
> useable condition at least, in 10 minutes of running. I accept,
> however, that this wasn't the case in days of yore when dynamos and
> mechanical regulators were the norm.
charge. And if they do and it is, may produce rather more than the nominal
12 volts. The best way is to charge the flat battery off the donor car for
a few minutes, if it has shown no signs of life. Then disconnect, and see
if the flat battery has taken a charge. if it has, proceed as normal. If
not, don't attempt a jump start.
> Maybe it's all different now, but I have jump started plenty of vehicles
> over the years that have ECUs, and using the 'rules' that I was taught,
> and have never had an issue. I have to say that being an electronics
> service person of many years experience myself, I am surprised that an
> ECU could be so readily damaged. Car electronics of any description -
> and particularly anything under the bonnet - have to cope with some of
> the most hostile conditions that could possibly be thrown at them, and
> that includes oceans of electrical noise and spikes, and I'm sure that
> the designers would incorporate the necessary protections into their
> circuitry to allow it to cope.
a failure by blaming it on the user.
--
*I used up all my sick days so I called in dead
Dave Plowman (News)
Mar 29, 2013, 7:20:00 AM3/29/13
to
In article <0nb5t.177037$%c5.2...@fx19.fr7>,
'open' type anyway?
--
*I don't work here. I'm a consultant
Chris Whelan <cawh...@prejudicentlworld.com> wrote:
> The problem is that when you make the last connection the two systems
> are at different voltages, so a spark may occur. It's likely that both
> batteries are gassing, so there's a *very* small chance of an explosion.
FFS, a battery doesn't 'gas' when flat. And when did you last see an
> The problem is that when you make the last connection the two systems
> are at different voltages, so a spark may occur. It's likely that both
> batteries are gassing, so there's a *very* small chance of an explosion.
'open' type anyway?
--
*I don't work here. I'm a consultant
Duncan Wood
Mar 29, 2013, 7:27:58 AM3/29/13
to
On Fri, 29 Mar 2013 11:08:08 -0000, Dave Plowman (News)
<da...@davenoise.co.uk> wrote:
> In article <op.wuolx...@duncan-tosh.cable.virginmedia.net>,
> Duncan Wood <nnt...@dmx512.co.uk> wrote:
>> >> > Load dump suppressor? Is that a polite name for a voltage
>> regulator?
>> >> >
>> >
>> >> No, the voltage reg controls the field coils, the suppressor either
>> >> directly trys to clamp the peak voltage or just crowbars the output.
>> >
>> > I'm talking about the voltage regulator in the ECU. The design of that
>> > should be perfectly capable of handling any spikes - even although
>> I'm
>> > not convinced they occur. If it can't, it's badly designed.
>
>> In that case they're all badly designed, they all regulate the field
>> current. Look up load dump, Bosch have published quite a lot on them,
>> there's a whole set of standardswritten
>
> You are saying every single new car has the alternator controlled by the
> engine management system?
No, you've just come up with that. Most aletrnator have the voltage reg
<da...@davenoise.co.uk> wrote:
> In article <op.wuolx...@duncan-tosh.cable.virginmedia.net>,
> Duncan Wood <nnt...@dmx512.co.uk> wrote:
>> >> > Load dump suppressor? Is that a polite name for a voltage
>> regulator?
>> >> >
>> >
>> >> No, the voltage reg controls the field coils, the suppressor either
>> >> directly trys to clamp the peak voltage or just crowbars the output.
>> >
>> > I'm talking about the voltage regulator in the ECU. The design of that
>> > should be perfectly capable of handling any spikes - even although
>> I'm
>> > not convinced they occur. If it can't, it's badly designed.
>
>> In that case they're all badly designed, they all regulate the field
>> current. Look up load dump, Bosch have published quite a lot on them,
>> there's a whole set of standardswritten
>
> You are saying every single new car has the alternator controlled by the
> engine management system?
built in, but they've never regulated the output, they regulate the
current in the field coils to control the output, so there's a lag.
> I find that very hard to believe. I know it is
> done with some. But in any case it makes no difference - a well designed
> one would provide protection on that input. After all, jump starting
> isn't
> exactly uncommon.
>
Duncan Wood
Mar 29, 2013, 7:29:46 AM3/29/13
to
On Fri, 29 Mar 2013 11:20:00 -0000, Dave Plowman (News)
<da...@davenoise.co.uk> wrote:
> In article <0nb5t.177037$%c5.2...@fx19.fr7>,
> Chris Whelan <cawh...@prejudicentlworld.com> wrote:
>> The problem is that when you make the last connection the two systems
>> are at different voltages, so a spark may occur. It's likely that both
>> batteries are gassing, so there's a *very* small chance of an explosion.
>
> FFS, a battery doesn't 'gas' when flat. And when did you last see an
> 'open' type anyway?
>
They gas when they're knakered & charging though, and you normally
<da...@davenoise.co.uk> wrote:
> In article <0nb5t.177037$%c5.2...@fx19.fr7>,
> Chris Whelan <cawh...@prejudicentlworld.com> wrote:
>> The problem is that when you make the last connection the two systems
>> are at different voltages, so a spark may occur. It's likely that both
>> batteries are gassing, so there's a *very* small chance of an explosion.
>
> FFS, a battery doesn't 'gas' when flat. And when did you last see an
> 'open' type anyway?
>
disconnect whilst they're charging.
Chris Whelan
Mar 29, 2013, 7:52:27 AM3/29/13
to
On Fri, 29 Mar 2013 11:08:08 +0000, Dave Plowman (News) wrote:
[...]
> You are saying every single new car has the alternator controlled by the
> engine management system? I find that very hard to believe.
Just about every Ford made since 1998 has.
> But in any case it makes no difference - a well designed
> one would provide protection on that input. After all, jump starting
> isn't exactly uncommon.
But it's not something a car manufacturer particularly cares about.
Ford cover themselves by detailing in their handbooks the method for
protecting against the disconnect surge.
[...]
> You are saying every single new car has the alternator controlled by the
> engine management system? I find that very hard to believe.
> But in any case it makes no difference - a well designed
> one would provide protection on that input. After all, jump starting
> isn't exactly uncommon.
Ford cover themselves by detailing in their handbooks the method for
protecting against the disconnect surge.
Chris Whelan
Mar 29, 2013, 7:56:06 AM3/29/13
to
On Fri, 29 Mar 2013 11:20:00 +0000, Dave Plowman (News) wrote:
[...]
[...]
> FFS, a battery doesn't 'gas' when flat. And when did you last see an
> 'open' type anyway?
What about when it's been cranking but not starting? For example, when
> 'open' type anyway?
trying to bleed a diesel? Or trying to start a flooded engine until the
battery dies? They certainly gas then.
Dave Plowman (News)
Mar 29, 2013, 9:58:18 AM3/29/13
to
In article <qjf5t.150667$Og1....@fx10.fr7>,
charge in a confined area? Hydrogen is one of the lightest of gasses, so
will not hang around. Generally, when a jump start is attempted, it's in
the open air.
--
* I like you. You remind me of when I was young and stupid
Chris Whelan <cawh...@prejudicentlworld.com> wrote:
> On Fri, 29 Mar 2013 11:20:00 +0000, Dave Plowman (News) wrote:
> [...]
> > FFS, a battery doesn't 'gas' when flat. And when did you last see an
> > 'open' type anyway?
> What about when it's been cranking but not starting? For example, when
> trying to bleed a diesel? Or trying to start a flooded engine until the
> battery dies? They certainly gas then.
Have you ever known a battery to explode through gassing? Except when on
> On Fri, 29 Mar 2013 11:20:00 +0000, Dave Plowman (News) wrote:
> [...]
> > FFS, a battery doesn't 'gas' when flat. And when did you last see an
> > 'open' type anyway?
> What about when it's been cranking but not starting? For example, when
> trying to bleed a diesel? Or trying to start a flooded engine until the
> battery dies? They certainly gas then.
charge in a confined area? Hydrogen is one of the lightest of gasses, so
will not hang around. Generally, when a jump start is attempted, it's in
the open air.
--
* I like you. You remind me of when I was young and stupid
Mrcheerful
Mar 29, 2013, 10:08:37 AM3/29/13
to
Dave Plowman (News) wrote:
> In article <qjf5t.150667$Og1....@fx10.fr7>,
> Chris Whelan <cawh...@prejudicentlworld.com> wrote:
>> On Fri, 29 Mar 2013 11:20:00 +0000, Dave Plowman (News) wrote:
>
>> [...]
>
>>> FFS, a battery doesn't 'gas' when flat. And when did you last see an
>>> 'open' type anyway?
>
>> What about when it's been cranking but not starting? For example,
>> when trying to bleed a diesel? Or trying to start a flooded engine
>> until the battery dies? They certainly gas then.
>
> Have you ever known a battery to explode through gassing? Except when
> on charge in a confined area? Hydrogen is one of the lightest of
> gasses, so will not hang around. Generally, when a jump start is
> attempted, it's in the open air.
I have blown up two by being careless, and it is not an experience to
> In article <qjf5t.150667$Og1....@fx10.fr7>,
> Chris Whelan <cawh...@prejudicentlworld.com> wrote:
>> On Fri, 29 Mar 2013 11:20:00 +0000, Dave Plowman (News) wrote:
>
>> [...]
>
>>> FFS, a battery doesn't 'gas' when flat. And when did you last see an
>>> 'open' type anyway?
>
>> What about when it's been cranking but not starting? For example,
>> when trying to bleed a diesel? Or trying to start a flooded engine
>> until the battery dies? They certainly gas then.
>
> Have you ever known a battery to explode through gassing? Except when
> on charge in a confined area? Hydrogen is one of the lightest of
> gasses, so will not hang around. Generally, when a jump start is
> attempted, it's in the open air.
repeat.
Tim+
Mar 29, 2013, 10:13:07 AM3/29/13
to
"Dave Plowman (News)" <da...@davenoise.co.uk> wrote:
> In article <qjf5t.150667$Og1....@fx10.fr7>,
> Chris Whelan <cawh...@prejudicentlworld.com> wrote:
>> On Fri, 29 Mar 2013 11:20:00 +0000, Dave Plowman (News) wrote:
>
>> [...]
>
>>> FFS, a battery doesn't 'gas' when flat. And when did you last see an
>>> 'open' type anyway?
>
>> What about when it's been cranking but not starting? For example, when
>> trying to bleed a diesel? Or trying to start a flooded engine until the
>> battery dies? They certainly gas then.
>
> Have you ever known a battery to explode through gassing? Except when on
> charge in a confined area? Hydrogen is one of the lightest of gasses, so
> will not hang around. Generally, when a jump start is attempted, it's in
> the open air.
Not quite an analogous situation but looks dodgy enough to me to be worth
> Chris Whelan <cawh...@prejudicentlworld.com> wrote:
>> On Fri, 29 Mar 2013 11:20:00 +0000, Dave Plowman (News) wrote:
>
>> [...]
>
>>> FFS, a battery doesn't 'gas' when flat. And when did you last see an
>>> 'open' type anyway?
>
>> What about when it's been cranking but not starting? For example, when
>> trying to bleed a diesel? Or trying to start a flooded engine until the
>> battery dies? They certainly gas then.
>
> Have you ever known a battery to explode through gassing? Except when on
> charge in a confined area? Hydrogen is one of the lightest of gasses, so
> will not hang around. Generally, when a jump start is attempted, it's in
> the open air.
taking precautions.
http://youtu.be/d_TnsHu2u4c
Tim
steve robinson
Mar 29, 2013, 10:22:23 AM3/29/13
to
Dave Plowman (News) wrote:
> In article <qjf5t.150667$Og1....@fx10.fr7>,
> Chris Whelan <cawh...@prejudicentlworld.com> wrote:
> > On Fri, 29 Mar 2013 11:20:00 +0000, Dave Plowman (News) wrote:
>
> > [...]
>
> > > FFS, a battery doesn't 'gas' when flat. And when did you last see
> > > an 'open' type anyway?
>
> > What about when it's been cranking but not starting? For example,
> > when trying to bleed a diesel? Or trying to start a flooded engine
> > until the battery dies? They certainly gas then.
>
> Have you ever known a battery to explode through gassing? Except when
> on charge in a confined area? Hydrogen is one of the lightest of
> gasses, so will not hang around. Generally, when a jump start is
> attempted, it's in the open air.
Yes my renault traffics battery exploded burning my hand
> In article <qjf5t.150667$Og1....@fx10.fr7>,
> Chris Whelan <cawh...@prejudicentlworld.com> wrote:
> > On Fri, 29 Mar 2013 11:20:00 +0000, Dave Plowman (News) wrote:
>
> > [...]
>
> > > FFS, a battery doesn't 'gas' when flat. And when did you last see
> > > an 'open' type anyway?
>
> > What about when it's been cranking but not starting? For example,
> > when trying to bleed a diesel? Or trying to start a flooded engine
> > until the battery dies? They certainly gas then.
>
> Have you ever known a battery to explode through gassing? Except when
> on charge in a confined area? Hydrogen is one of the lightest of
> gasses, so will not hang around. Generally, when a jump start is
> attempted, it's in the open air.
Dave Plowman (News)
Mar 29, 2013, 11:07:42 AM3/29/13
to
In article <rhh5t.127612$971....@fx14.fr7>,
when in a small charging area of a garage which is likely full of hydrogen
from the many batteries. These days I'd expect it to be properly
ventilated.
--
*ONE NICE THING ABOUT EGOTISTS: THEY DON'T TALK ABOUT OTHER PEOPLE.
Mrcheerful <g.odon...@yahoo.co.uk> wrote:
> > Have you ever known a battery to explode through gassing? Except when
> > on charge in a confined area? Hydrogen is one of the lightest of
> > gasses, so will not hang around. Generally, when a jump start is
> > attempted, it's in the open air.
> I have blown up two by being careless, and it is not an experience to
> repeat.
Care to give the exact circumstances? As I said I've know them blow up
> > Have you ever known a battery to explode through gassing? Except when
> > on charge in a confined area? Hydrogen is one of the lightest of
> > gasses, so will not hang around. Generally, when a jump start is
> > attempted, it's in the open air.
> I have blown up two by being careless, and it is not an experience to
> repeat.
when in a small charging area of a garage which is likely full of hydrogen
from the many batteries. These days I'd expect it to be properly
ventilated.
--
*ONE NICE THING ABOUT EGOTISTS: THEY DON'T TALK ABOUT OTHER PEOPLE.
Paul Giverin
Mar 29, 2013, 12:52:27 PM3/29/13
to
In message <rhh5t.127612$971....@fx14.fr7>, Mrcheerful
<g.odon...@yahoo.co.uk> writes
you do it twice?
;)
--
Paul Giverin
My Photos:- www.giverin.co.uk
<g.odon...@yahoo.co.uk> writes
>Dave Plowman (News) wrote:
>>
>> Have you ever known a battery to explode through gassing? Except when
>> on charge in a confined area? Hydrogen is one of the lightest of
>> gasses, so will not hang around. Generally, when a jump start is
>> attempted, it's in the open air.
>
>I have blown up two by being careless, and it is not an experience to
>repeat.
>
Well someone's got to ask, if its not an experience to repeat, why did
>>
>> Have you ever known a battery to explode through gassing? Except when
>> on charge in a confined area? Hydrogen is one of the lightest of
>> gasses, so will not hang around. Generally, when a jump start is
>> attempted, it's in the open air.
>
>I have blown up two by being careless, and it is not an experience to
>repeat.
>
you do it twice?
;)
--
Paul Giverin
My Photos:- www.giverin.co.uk
Mrcheerful
Mar 29, 2013, 2:03:16 PM3/29/13
to
but fairly similar, the second was caused by inattention, the first by
careless handling.
Mrcheerful
Mar 29, 2013, 2:12:27 PM3/29/13
to
Dave Plowman (News) wrote:
> In article <rhh5t.127612$971....@fx14.fr7>,
> Mrcheerful <g.odon...@yahoo.co.uk> wrote:
>>> Have you ever known a battery to explode through gassing? Except
>>> when on charge in a confined area? Hydrogen is one of the lightest
>>> of gasses, so will not hang around. Generally, when a jump start is
>>> attempted, it's in the open air.
>
>> I have blown up two by being careless, and it is not an experience to
>> repeat.
>
> Care to give the exact circumstances? As I said I've know them blow up
> when in a small charging area of a garage which is likely full of
> hydrogen from the many batteries. These days I'd expect it to be
> properly ventilated.
The first was when I had fitted a secondhand engine to a MK1 escort, the
> In article <rhh5t.127612$971....@fx14.fr7>,
> Mrcheerful <g.odon...@yahoo.co.uk> wrote:
>>> Have you ever known a battery to explode through gassing? Except
>>> when on charge in a confined area? Hydrogen is one of the lightest
>>> of gasses, so will not hang around. Generally, when a jump start is
>>> attempted, it's in the open air.
>
>> I have blown up two by being careless, and it is not an experience to
>> repeat.
>
> Care to give the exact circumstances? As I said I've know them blow up
> when in a small charging area of a garage which is likely full of
> hydrogen from the many batteries. These days I'd expect it to be
> properly ventilated.
owner was there and it did not want to start, as the battery was down I
connected up the seriously big Crypton charger and turned it up a bit while
I fiddled about, I accidentally knocked one of the crocodiles and blam,
luckily it just blew out a couple of filler plugs. I said that it was just
something that happened occasionally when charging batteries.
The second time was about twenty years later, inside my camper van, the
batteries are under the floor and open to the air, both had been on charge
after winter disuse. The camper was not spinning over quick enough to
start, so I connected the jump pack, in the dark depths I failed to get the
polarity right and serious blam occurred, I was showered in acid (as the
case ruptured), as was the interior of the camper, happily none went in my
eyes or caused any damage to me or the camper, I was very, very lucky.
tony sayer
Mar 30, 2013, 3:31:34 PM3/30/13
to
In article <kj1nk5$308$1...@dont-email.me>, TMack <qw...@yuiop.com>
scribeth thus
reasoned scientific detailed explanation as to -why- this happens.
Has anyone done any research that's publicly available on this anywhere
at all?...
--
Tony Sayer
scribeth thus
>On Thu, 28 Mar 2013 13:30:31 +0000, Chris Whelan wrote:
>> The repairer told him that ECU's fried after jump-
>> starting were so common, it was the first question he asked when someone
>> phoned him for advice.
>
>This is a classic case of a correlation NOT providing proof of a causal
>relationship. For example - many people whose vehicles won't start will
>keep trying until the battery is too flat to turn the engine. The next
>thing they try is a jump start... An ECU fault may have been the reason
>for the original non-starting - but it is subsequently interpreted as
>having been *caused* by the attempts to jump start.
>> The repairer told him that ECU's fried after jump-
>> starting were so common, it was the first question he asked when someone
>> phoned him for advice.
>
>This is a classic case of a correlation NOT providing proof of a causal
>relationship. For example - many people whose vehicles won't start will
>keep trying until the battery is too flat to turn the engine. The next
>thing they try is a jump start... An ECU fault may have been the reason
>for the original non-starting - but it is subsequently interpreted as
>
>It is possible that jump starts are the major cause of ECU failure but it
>would take more than an anecdotal account of a correlation to provide good
>evidence for the causal relationship.
>
As prolly one of the original nay-sayers I still haven't found a logical
>It is possible that jump starts are the major cause of ECU failure but it
>would take more than an anecdotal account of a correlation to provide good
>evidence for the causal relationship.
>
reasoned scientific detailed explanation as to -why- this happens.
Has anyone done any research that's publicly available on this anywhere
at all?...
--
Tony Sayer
tony sayer
Mar 30, 2013, 3:35:13 PM3/30/13
to
>
>Re-read my original post; It's addressed 'To the nay-sayers...'
>
>There are some regulars who post here who in the past *have* said that
>jump-starting cannot spike an ECU.
>
>> I simply disputed that the *evidence
>> presented* was sufficient to support the view that jump starts are the
>> main cause of ECU failure. It might be true but one would need better
>> evidence before coming to that conclusion.
>
>I never said that jump-starts are the *main* cause of ECU failure; I said
>that the company that repairs them finds that it's a common reason for
>such failures.
>
Do those companies ever say -why- the problem was caused?...
>Re-read my original post; It's addressed 'To the nay-sayers...'
>
>There are some regulars who post here who in the past *have* said that
>jump-starting cannot spike an ECU.
>
>> I simply disputed that the *evidence
>> presented* was sufficient to support the view that jump starts are the
>> main cause of ECU failure. It might be true but one would need better
>> evidence before coming to that conclusion.
>
>I never said that jump-starts are the *main* cause of ECU failure; I said
>that the company that repairs them finds that it's a common reason for
>such failures.
>
Or do they just change the chip/s transistor/r whatever as thats the one
thats duff and will put right the fault?..
>Chris
>
--
Tony Sayer
Duncan Wood
Mar 31, 2013, 6:30:17 PM3/31/13
to
winding, so if the alternators delivering current into the battery on the
donor vehicle & it's battery is knackered when you disconnect the jump
leads there's a large dc current flowing & no easy way of reducing it.
Bosch and all the major semiconductor manufacturers have info, & there's
an ISO standard for measuring & simulating it. If you've still got an
ACR17 then it's probably not worth worrying about though.
Dave Plowman (News)
Mar 31, 2013, 7:25:28 PM3/31/13
to
In article <op.wut0s...@duncan-tosh.lan>,
Duncan Wood <nnt...@dmx512.co.uk> wrote:
> Google alternator load dump,
I'd rather not, since so much is speculation.
> the regulator only controls the field winding, so if the alternators
> delivering current into the battery on the donor vehicle & it's
> battery is knackered when you disconnect the jump leads there's a
> large dc current flowing & no easy way of reducing it.
What has current got to do with it? To have a large 'current' flow into
the ECU, it would have to have a low impedance.
> Bosch and all the major semiconductor manufacturers have info, & there's
> an ISO standard for measuring & simulating it. If you've still got an
> ACR17 then it's probably not worth worrying about though.
--
*I didn't drive my husband crazy -- I flew him there -- it was faster
Duncan Wood <nnt...@dmx512.co.uk> wrote:
> Google alternator load dump,
I'd rather not, since so much is speculation.
> the regulator only controls the field winding, so if the alternators
> delivering current into the battery on the donor vehicle & it's
> battery is knackered when you disconnect the jump leads there's a
> large dc current flowing & no easy way of reducing it.
the ECU, it would have to have a low impedance.
> Bosch and all the major semiconductor manufacturers have info, & there's
> an ISO standard for measuring & simulating it. If you've still got an
> ACR17 then it's probably not worth worrying about though.
*I didn't drive my husband crazy -- I flew him there -- it was faster
Arfa Daily
Mar 31, 2013, 8:50:05 PM3/31/13
to
"tony sayer" <to...@bancom.co.uk> wrote in message
news:zdHv5WDx...@bancom.co.uk...
that by far, the biggest problem is simple dry joints ...
Arfa
Arfa Daily
Mar 31, 2013, 9:28:05 PM3/31/13
to
"Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
news:533546b...@davenoise.co.uk...
> In article <op.wut0s...@duncan-tosh.lan>,
> Duncan Wood <nnt...@dmx512.co.uk> wrote:
>> Google alternator load dump,
> I'd rather not, since so much is speculation.
I took the trouble to have a look at the top reference, which was the Wiki
> Duncan Wood <nnt...@dmx512.co.uk> wrote:
>> Google alternator load dump,
> I'd rather not, since so much is speculation.
one. It seems to contradict itself line by line, but the basic premise is
that if the battery is *disconnected* whilst the alternator is trying to
charge it, an over-voltage condition will be produced due to the fact that
the alternator control circuitry had the field windings being supplied with
the appropriate current to keep the alternator 'wide open' in order to be
supplying the maximum charging current to the battery. The contention is
that the alternator will continue to generate a large current that now has
nowhere to go, other than into other things attached to the battery, for up
to 400 mS before the field winding current is reduced by the ECU to
'throttle back' the alternator. One such connected item is the ECU itself,
and it is implied that this large current which continues to be generated,
can cause a peak voltage of up to 120 volts to be applied to the ECU, which
is what kills it.
Well, quite apart from the pseudo-science in all that, where the author
seems to be mixing current and voltage willy nilly to arrive at a
conclusion, two things come to mind. First, unless the receiver battery has
an open circuit cell, disconnecting the feed from the donor vehicle should
have little effect, as by far, the largest load on the alternator will be
the flat receiver battery, which will continue to drag as much current from
its own alternator as it will let it have. The donor battery / alternator
should not have any effect on the current demand of the receiver battery
from its own alternator, as the donor is a net exporter of current to the
flat receiver battery.
Secondly, the article does go on to say that there are published spike shape
specifications for the electronics designers to design against, and it
mentions varistors and similar protection devices that could be employed.
These are not esoteric devices. They are in extremely common usage right
across the field of electronics design from domestic to industrial, and are
employed anywhere that a troublesome voltage spike is likely to occur. They
are fast and extremely good at what they do, and above all, are cheap. Using
one, or a similar device, to protect the ECU against a 120v pulse on its
supply rail would, IMHO, be the very least that a good designer would do to
protect his 'delicate' circuitry from the extremely electrically hostile
environment that the outside world represents in an automotive application.
I would have thought that pulses of 120 v plus kicking about on the wiring
of a vehicle, would be the rule rather than the exception. Considering that
the cranking current of the starter motor can start out at over 100 amps,
and continue to be 40 or more until the engine starts, and that that load
then suddenly disappears as the starter is thrown out disengaging the
solenoid switch, is likely to cause significant spikes. Even a bit of a bad
plug lead, could cause large spikes to be induced in nearby wiring. I can't
actually imagine that any designer employed in the intensive world of
competitive automotive electronics, would not protect every rail and input
or output on his designs, with the cheap and effective devices available for
exactly this purpose, and if it is indeed the norm that this protection is
*not* designed in, then I am surprised that there are any cars still running
at all ...
Arfa
Duncan Wood
Apr 1, 2013, 6:29:07 AM4/1/13
to
On Mon, 01 Apr 2013 02:28:05 +0100, Arfa Daily <arfa....@ntlworld.com>
wrote:
>
>
> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
> news:533546b...@davenoise.co.uk...
>> In article <op.wut0s...@duncan-tosh.lan>,
>> Duncan Wood <nnt...@dmx512.co.uk> wrote:
>>> Google alternator load dump,
>> I'd rather not, since so much is speculation.
>
> I took the trouble to have a look at the top reference, which was the
> Wiki one. It seems to contradict itself line by line, but the basic
> premise is that if the battery is *disconnected* whilst the alternator
> is trying to charge it, an over-voltage condition will be produced due
> to the fact that the alternator control circuitry had the field windings
> being supplied with the appropriate current to keep the alternator 'wide
> open' in order to be supplying the maximum charging current to the
> battery. The contention is that the alternator will continue to generate
> a large current that now has nowhere to go, other than into other things
> attached to the battery, for up to 400 mS before the field winding
> current is reduced by the ECU to 'throttle back' the alternator.
On most cars the ECU doesn't have anything to do with controling the
alternator, it's got it's own regulator
> One such connected item is the ECU itself, and it is implied that this
> large current which continues to be generated, can cause a peak voltage
> of up to 120 volts to be applied to the ECU, which is what kills it.
>
> Well, quite apart from the pseudo-science in all that, where the author
> seems to be mixing current and voltage willy nilly to arrive at a
> conclusion, two things come to mind.
> First, unless the receiver battery has an open circuit cell,
> disconnecting the feed from the donor vehicle should have little effect,
> as by far, the largest load on the alternator will be the flat receiver
> battery, which will continue to drag as much current from its own
> alternator as it will let it have.
Which is why it's fairly rare, unless you've got a fault with the battery
then you'll be fine.
wrote:
>
>
> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
> news:533546b...@davenoise.co.uk...
>> In article <op.wut0s...@duncan-tosh.lan>,
>> Duncan Wood <nnt...@dmx512.co.uk> wrote:
>>> Google alternator load dump,
>> I'd rather not, since so much is speculation.
>
> I took the trouble to have a look at the top reference, which was the
> Wiki one. It seems to contradict itself line by line, but the basic
> premise is that if the battery is *disconnected* whilst the alternator
> is trying to charge it, an over-voltage condition will be produced due
> to the fact that the alternator control circuitry had the field windings
> being supplied with the appropriate current to keep the alternator 'wide
> open' in order to be supplying the maximum charging current to the
> battery. The contention is that the alternator will continue to generate
> a large current that now has nowhere to go, other than into other things
> attached to the battery, for up to 400 mS before the field winding
> current is reduced by the ECU to 'throttle back' the alternator.
alternator, it's got it's own regulator
> One such connected item is the ECU itself, and it is implied that this
> large current which continues to be generated, can cause a peak voltage
> of up to 120 volts to be applied to the ECU, which is what kills it.
>
> Well, quite apart from the pseudo-science in all that, where the author
> seems to be mixing current and voltage willy nilly to arrive at a
> conclusion, two things come to mind.
> First, unless the receiver battery has an open circuit cell,
> disconnecting the feed from the donor vehicle should have little effect,
> as by far, the largest load on the alternator will be the flat receiver
> battery, which will continue to drag as much current from its own
> alternator as it will let it have.
then you'll be fine.
Dave Plowman (News)
Apr 1, 2013, 6:56:28 AM4/1/13
to
Pretty spot on Arfa. Indeed, voltage regulators used on car electronics
have already (or should have) a higher spec than the ones you'll find on
most other things - ie a higher allowed input voltage.
It's certainly possible for an alternator with no load on it but the field
coils driven to produce far higher voltages than designed to. Hence the
reason to check the battery isn't totally dead, and will take a charge.
And adding some form of surge suppressor when jump starting won't prevent
this high voltage when the donor battery is disconnected under this sort
of fault condition.
--
*They call it PMS because Mad Cow Disease was already taken.
have already (or should have) a higher spec than the ones you'll find on
most other things - ie a higher allowed input voltage.
It's certainly possible for an alternator with no load on it but the field
coils driven to produce far higher voltages than designed to. Hence the
reason to check the battery isn't totally dead, and will take a charge.
And adding some form of surge suppressor when jump starting won't prevent
this high voltage when the donor battery is disconnected under this sort
of fault condition.
--
*They call it PMS because Mad Cow Disease was already taken.
Duncan Wood
Apr 1, 2013, 7:05:13 AM4/1/13
to
On Mon, 01 Apr 2013 11:56:28 +0100, Dave Plowman (News)
<da...@davenoise.co.uk> wrote:
> Pretty spot on Arfa. Indeed, voltage regulators used on car electronics
> have already (or should have) a higher spec than the ones you'll find on
> most other things - ie a higher allowed input voltage.
>
They do indeed, just not always high enough.
<da...@davenoise.co.uk> wrote:
> Pretty spot on Arfa. Indeed, voltage regulators used on car electronics
> have already (or should have) a higher spec than the ones you'll find on
> most other things - ie a higher allowed input voltage.
>
> It's certainly possible for an alternator with no load on it but the
> field
> coils driven to produce far higher voltages than designed to. Hence the
> reason to check the battery isn't totally dead, and will take a charge.
> And adding some form of surge suppressor when jump starting won't prevent
> this high voltage when the donor battery is disconnected under this sort
> of fault condition.
>
steve robinson
Apr 1, 2013, 7:29:56 AM4/1/13
to
Dave Plowman (News) wrote:
> Pretty spot on Arfa. Indeed, voltage regulators used on car
> electronics have already (or should have) a higher spec than the ones
> you'll find on most other things - ie a higher allowed input voltage.
>
>
> It's certainly possible for an alternator with no load on it but the
> field coils driven to produce far higher voltages than designed to.
> Hence the reason to check the battery isn't totally dead, and will
> take a charge. And adding some form of surge suppressor when jump
> starting won't prevent this high voltage when the donor battery is
> disconnected under this sort of fault condition.
No it wont but it will dissipate its effects.
> Pretty spot on Arfa. Indeed, voltage regulators used on car
> electronics have already (or should have) a higher spec than the ones
> you'll find on most other things - ie a higher allowed input voltage.
>
>
> It's certainly possible for an alternator with no load on it but the
> field coils driven to produce far higher voltages than designed to.
> Hence the reason to check the battery isn't totally dead, and will
> take a charge. And adding some form of surge suppressor when jump
> starting won't prevent this high voltage when the donor battery is
> disconnected under this sort of fault condition.
Any circuit with inductive loads can cause a power spike, if the
circuits are interfeared with, its just as possible the spike could
be on the ground side of the circuit.
Its rare but it does happen
Dave Plowman (News)
Apr 1, 2013, 7:44:51 AM4/1/13
to
In article <op.wuuzq...@duncan-tosh.lan>,
employed. It's hardly rocket science. But the very fact that 'better' (and
more expensive) regulators specifically for car use are available means
it's not necessary.
> > It's certainly possible for an alternator with no load on it but the
> > field
> > coils driven to produce far higher voltages than designed to. Hence the
> > reason to check the battery isn't totally dead, and will take a charge.
> Good idea but somewhat impractical in most jump starts
Turn on the ignition on the car - any signs of life? If not, don't attempt
a jump start.
> > And adding some form of surge suppressor when jump starting won't
> > prevent this high voltage when the donor battery is disconnected under
> > this sort of fault condition.
> >
> Err why not, you disconnect the donor battery from the surge supressor
> 1st.
Fine if you leave the suppressor permanently in circuit. But if the 'flat'
battery is knackered, the volts will still surge upwards when you remove
it.
--
*The problem with the world is that everyone is a few drinks behind *
Duncan Wood <nnt...@dmx512.co.uk> wrote:
> On Mon, 01 Apr 2013 11:56:28 +0100, Dave Plowman (News)
> <da...@davenoise.co.uk> wrote:
> > Pretty spot on Arfa. Indeed, voltage regulators used on car
> > electronics have already (or should have) a higher spec than the ones
> > you'll find on most other things - ie a higher allowed input voltage.
> >
> They do indeed, just not always high enough.
Then additional means of preventing over voltage damage should be
> On Mon, 01 Apr 2013 11:56:28 +0100, Dave Plowman (News)
> <da...@davenoise.co.uk> wrote:
> > Pretty spot on Arfa. Indeed, voltage regulators used on car
> > electronics have already (or should have) a higher spec than the ones
> > you'll find on most other things - ie a higher allowed input voltage.
> >
> They do indeed, just not always high enough.
employed. It's hardly rocket science. But the very fact that 'better' (and
more expensive) regulators specifically for car use are available means
it's not necessary.
> > It's certainly possible for an alternator with no load on it but the
> > field
> > coils driven to produce far higher voltages than designed to. Hence the
> > reason to check the battery isn't totally dead, and will take a charge.
> Good idea but somewhat impractical in most jump starts
a jump start.
> > And adding some form of surge suppressor when jump starting won't
> > prevent this high voltage when the donor battery is disconnected under
> > this sort of fault condition.
> >
> Err why not, you disconnect the donor battery from the surge supressor
> 1st.
battery is knackered, the volts will still surge upwards when you remove
it.
--
*The problem with the world is that everyone is a few drinks behind *
Arfa Daily
Apr 1, 2013, 8:07:34 AM4/1/13
to
"steve robinson" <st...@colevalleyinteriors.co.uk> wrote in message
news:xn0igay7...@reader80.eternal-september.org...
reference. However, the point I made about utilizing varistors or whatever
on inputs and outputs of car electronics, remains valid, as these devices
are placed between the line to be protected, and this arbitrary ground, and
the device doesn't really care which of its legs 'spikes' with respect to
the other.
Arfa
Arfa Daily
Apr 1, 2013, 8:18:07 AM4/1/13
to
"Duncan Wood" <nnt...@dmx512.co.uk> wrote in message
news:op.wuux2...@duncan-tosh.lan...
> On Mon, 01 Apr 2013 02:28:05 +0100, Arfa Daily <arfa....@ntlworld.com>
> wrote:
>
>>
>>
>> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
>> news:533546b...@davenoise.co.uk...
>>> In article <op.wut0s...@duncan-tosh.lan>,
>>> Duncan Wood <nnt...@dmx512.co.uk> wrote:
>>>> Google alternator load dump,
>>> I'd rather not, since so much is speculation.
>>
>> I took the trouble to have a look at the top reference, which was the
>> Wiki one. It seems to contradict itself line by line, but the basic
>> premise is that if the battery is *disconnected* whilst the alternator
>> is trying to charge it, an over-voltage condition will be produced due
>> to the fact that the alternator control circuitry had the field windings
>> being supplied with the appropriate current to keep the alternator 'wide
>> open' in order to be supplying the maximum charging current to the
>> battery. The contention is that the alternator will continue to generate
>> a large current that now has nowhere to go, other than into other things
>> attached to the battery, for up to 400 mS before the field winding
>> current is reduced by the ECU to 'throttle back' the alternator.
>
> On most cars the ECU doesn't have anything to do with controling the
> alternator, it's got it's own regulator
<snip>
> wrote:
>
>>
>>
>> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
>> news:533546b...@davenoise.co.uk...
>>> In article <op.wut0s...@duncan-tosh.lan>,
>>> Duncan Wood <nnt...@dmx512.co.uk> wrote:
>>>> Google alternator load dump,
>>> I'd rather not, since so much is speculation.
>>
>> I took the trouble to have a look at the top reference, which was the
>> Wiki one. It seems to contradict itself line by line, but the basic
>> premise is that if the battery is *disconnected* whilst the alternator
>> is trying to charge it, an over-voltage condition will be produced due
>> to the fact that the alternator control circuitry had the field windings
>> being supplied with the appropriate current to keep the alternator 'wide
>> open' in order to be supplying the maximum charging current to the
>> battery. The contention is that the alternator will continue to generate
>> a large current that now has nowhere to go, other than into other things
>> attached to the battery, for up to 400 mS before the field winding
>> current is reduced by the ECU to 'throttle back' the alternator.
>
> On most cars the ECU doesn't have anything to do with controling the
> alternator, it's got it's own regulator
Agreed, that certainly used to be the case at least. However, I'm sure that
I read somewhere that all alternators used by Ford were now intelligent ones
controlled from the ECU, and had been for some time. Could be wrong on that,
and if so, I bow to your trade knowledge. However, if most alternators *do*
still employ their own regulator, then the situation for disconnection
causing a big spike problem, becomes even more odd. I can see a control loop
that runs through the ECU taking 400 mS to respond, may be a valid scenario
(although with modern multitasking processors taking only a few clocks to
execute even complex instructions, that still feels slow) but if a discrete
regulator inside the alternator takes that long, it must be pretty poorly
designed ?
Arfa
steve robinson
Apr 1, 2013, 8:36:41 AM4/1/13
to
just not practical
Dave Plowman (News)
Apr 1, 2013, 9:18:26 AM4/1/13
to
In article <xn0igay7...@reader80.eternal-september.org>,
does produce vast spikes when the current is removed. It also takes rather
more 'current' than the alternator produces - and according to these
articles it's 'high current spikes' that cause the problem. And of course,
all ignition systems operate on just this principle. The primary device
that prevents these spikes from doing damage is the very low impedance
battery - and the way things are wired from it. It is already a very
efficent surge suppressor.
--
*Caution: I drive like you do.
steve robinson <st...@colevalleyinteriors.co.uk> wrote:
> > It's certainly possible for an alternator with no load on it but the
> > field coils driven to produce far higher voltages than designed to.
> > Hence the reason to check the battery isn't totally dead, and will
> > take a charge. And adding some form of surge suppressor when jump
> > starting won't prevent this high voltage when the donor battery is
> > disconnected under this sort of fault condition.
> No it wont but it will dissipate its effects.
> Any circuit with inductive loads can cause a power spike, if the
> circuits are interfeared with, its just as possible the spike could
> be on the ground side of the circuit.
> Its rare but it does happen
The biggest inductive load on a car is the starter motor. Which certainly
> > It's certainly possible for an alternator with no load on it but the
> > field coils driven to produce far higher voltages than designed to.
> > Hence the reason to check the battery isn't totally dead, and will
> > take a charge. And adding some form of surge suppressor when jump
> > starting won't prevent this high voltage when the donor battery is
> > disconnected under this sort of fault condition.
> No it wont but it will dissipate its effects.
> Any circuit with inductive loads can cause a power spike, if the
> circuits are interfeared with, its just as possible the spike could
> be on the ground side of the circuit.
> Its rare but it does happen
does produce vast spikes when the current is removed. It also takes rather
more 'current' than the alternator produces - and according to these
articles it's 'high current spikes' that cause the problem. And of course,
all ignition systems operate on just this principle. The primary device
that prevents these spikes from doing damage is the very low impedance
battery - and the way things are wired from it. It is already a very
efficent surge suppressor.
--
*Caution: I drive like you do.
Dave Plowman (News)
Apr 1, 2013, 9:23:02 AM4/1/13
to
In article <4We6t.238131$fe2.2...@fx32.fr7>,
difference is it communicates with the engine ECU.
--
*Modulation in all things *
Arfa Daily <arfa....@ntlworld.com> wrote:
> Agreed, that certainly used to be the case at least. However, I'm sure
> that I read somewhere that all alternators used by Ford were now
> intelligent ones controlled from the ECU, and had been for some time.
> Could be wrong on that, and if so, I bow to your trade knowledge.
> However, if most alternators *do* still employ their own regulator,
> then the situation for disconnection causing a big spike problem,
> becomes even more odd. I can see a control loop that runs through the
> ECU taking 400 mS to respond, may be a valid scenario (although with
> modern multitasking processors taking only a few clocks to execute even
> complex instructions, that still feels slow) but if a discrete
> regulator inside the alternator takes that long, it must be pretty
> poorly designed ?
The main part of the alternator regulator is still in the alternator. The
> Agreed, that certainly used to be the case at least. However, I'm sure
> that I read somewhere that all alternators used by Ford were now
> intelligent ones controlled from the ECU, and had been for some time.
> Could be wrong on that, and if so, I bow to your trade knowledge.
> However, if most alternators *do* still employ their own regulator,
> then the situation for disconnection causing a big spike problem,
> becomes even more odd. I can see a control loop that runs through the
> ECU taking 400 mS to respond, may be a valid scenario (although with
> modern multitasking processors taking only a few clocks to execute even
> complex instructions, that still feels slow) but if a discrete
> regulator inside the alternator takes that long, it must be pretty
> poorly designed ?
difference is it communicates with the engine ECU.
--
*Modulation in all things *
Dave Plowman (News)
Apr 1, 2013, 9:21:19 AM4/1/13
to
In article <xn0igazy...@reader80.eternal-september.org>,
this scenario? Never any of the other multitude of electronics on a modern
car? So just how is it not practical to protect it if needed?
--
*Before they invented drawing boards, what did they go back to?
steve robinson <st...@colevalleyinteriors.co.uk> wrote:
> > Quite so, as in the case of a car, the term "ground" is just an
> > arbitrary reference. However, the point I made about utilizing
> > varistors or whatever on inputs and outputs of car electronics,
> > remains valid, as these devices are placed between the line to be
> > protected, and this arbitrary ground, and the device doesn't really
> > care which of its legs 'spikes' with respect to the other.
> >
> > Arfa
> varistors serve a purpose but they cant be inserted in every cuircit
> just not practical
Have you not noticed that it's always only the ECU which is damaged by
> > Quite so, as in the case of a car, the term "ground" is just an
> > arbitrary reference. However, the point I made about utilizing
> > varistors or whatever on inputs and outputs of car electronics,
> > remains valid, as these devices are placed between the line to be
> > protected, and this arbitrary ground, and the device doesn't really
> > care which of its legs 'spikes' with respect to the other.
> >
> > Arfa
> varistors serve a purpose but they cant be inserted in every cuircit
> just not practical
this scenario? Never any of the other multitude of electronics on a modern
car? So just how is it not practical to protect it if needed?
--
*Before they invented drawing boards, what did they go back to?
steve robinson
Apr 1, 2013, 9:36:57 AM4/1/13
to
soleniod or relay setup so any current spike dumps straight into the
ground circuit
Alternators dont operate in the same way , for a start they generate
AC not DC which has to be rectified usally by a diode pack sudden
diodes dont like sudden surges
Chris Whelan
Apr 1, 2013, 9:40:23 AM4/1/13
to
On Mon, 01 Apr 2013 13:18:07 +0100, Arfa Daily wrote:
[...]
>> On most cars the ECU doesn't have anything to do with controling the
>> alternator, it's got it's own regulator
>
> <snip>
>
> Agreed, that certainly used to be the case at least. However, I'm sure
> that I read somewhere that all alternators used by Ford were now
> intelligent ones controlled from the ECU, and had been for some time.
In addition to Ford Smart Charge (introduced ~1998):
http://bit.ly/U5seGl
many cars use the ECU to effectively turn the alternator output off when
the lights are not in use and the battery is at least partially charged.
The alternator is only put back 'on load' when the ECU senses an over-run
condition. Obviously this is a fuel saving strategy
BMW have done this on some models from 2006; their system is called
Intelligent Alternator Control. Later Disco's turn the alternator off at
tickover.
Incidentally, the author of the above link suggests that Ford vehicles
with Smart Charge and a flat battery should *never* be jump-started!
Chris
--
Remove prejudice to reply.
[...]
>> On most cars the ECU doesn't have anything to do with controling the
>> alternator, it's got it's own regulator
>
> <snip>
>
> Agreed, that certainly used to be the case at least. However, I'm sure
> that I read somewhere that all alternators used by Ford were now
> intelligent ones controlled from the ECU, and had been for some time.
http://bit.ly/U5seGl
many cars use the ECU to effectively turn the alternator output off when
the lights are not in use and the battery is at least partially charged.
The alternator is only put back 'on load' when the ECU senses an over-run
condition. Obviously this is a fuel saving strategy
BMW have done this on some models from 2006; their system is called
Intelligent Alternator Control. Later Disco's turn the alternator off at
tickover.
Incidentally, the author of the above link suggests that Ford vehicles
with Smart Charge and a flat battery should *never* be jump-started!
Chris
--
Remove prejudice to reply.
steve robinson
Apr 1, 2013, 9:45:14 AM4/1/13
to
Dave Plowman (News) wrote:
> In article <xn0igazy...@reader80.eternal-september.org>,
> steve robinson <st...@colevalleyinteriors.co.uk> wrote:
> > > Quite so, as in the case of a car, the term "ground" is just an
> > > arbitrary reference. However, the point I made about utilizing
> > > varistors or whatever on inputs and outputs of car electronics,
> > > remains valid, as these devices are placed between the line to be
> > > protected, and this arbitrary ground, and the device doesn't
> > > really care which of its legs 'spikes' with respect to the other.
> > >
> > > Arfa
>
> > varistors serve a purpose but they cant be inserted in every cuircit
> > just not practical
>
> Have you not noticed that it's always only the ECU which is damaged by
> this scenario? Never any of the other multitude of electronics on a
> modern car? So just how is it not practical to protect it if needed?
Some of the ecu operations cant be fed through circuits with these
> In article <xn0igazy...@reader80.eternal-september.org>,
> steve robinson <st...@colevalleyinteriors.co.uk> wrote:
> > > Quite so, as in the case of a car, the term "ground" is just an
> > > arbitrary reference. However, the point I made about utilizing
> > > varistors or whatever on inputs and outputs of car electronics,
> > > remains valid, as these devices are placed between the line to be
> > > protected, and this arbitrary ground, and the device doesn't
> > > really care which of its legs 'spikes' with respect to the other.
> > >
> > > Arfa
>
> > varistors serve a purpose but they cant be inserted in every cuircit
> > just not practical
>
> Have you not noticed that it's always only the ECU which is damaged by
> this scenario? Never any of the other multitude of electronics on a
> modern car? So just how is it not practical to protect it if needed?
components fitted .
ECUs have different operating voltages for some functions , within
the electronics of a car you can create a voltage differential of
nearly 30 volts if required you can have - feed + feed to a ground ,
split rail grounds all within the ecu plus ac
Arfa Daily
Apr 1, 2013, 9:46:23 AM4/1/13
to
"Chris Whelan" <cawh...@prejudicentlworld.com> wrote in message
news:b7g6t.264413$fB.1...@fx27.fr7...
Arfa
Steve Firth
Apr 1, 2013, 9:48:36 AM4/1/13
to
"Dave Plowman (News)" <da...@davenoise.co.uk> wrote:
[snip]
head unit and amp in the Jeep because erindoors got a jump start.
Fried the memory in the mirror and blew heavens knows what in the stereo.
Deader than corduroy flares.
The ECU and the LPG controller are both fine.
--
<•DarWin><|
_/ _/
[snip]
>
> Have you not noticed that it's always only the ECU which is damaged by
> this scenario? Never any of the other multitude of electronics on a modern
> car? So just how is it not practical to protect it if needed?
Actually it's not. I've just had to replace a wing mirror and the Infinity
> Have you not noticed that it's always only the ECU which is damaged by
> this scenario? Never any of the other multitude of electronics on a modern
> car? So just how is it not practical to protect it if needed?
head unit and amp in the Jeep because erindoors got a jump start.
Fried the memory in the mirror and blew heavens knows what in the stereo.
Deader than corduroy flares.
The ECU and the LPG controller are both fine.
--
<•DarWin><|
_/ _/
Duncan Wood
Apr 1, 2013, 10:06:47 AM4/1/13
to
On Mon, 01 Apr 2013 12:44:51 +0100, Dave Plowman (News)
Why? The surge suppressor won't pull any current?
Duncan Wood
Apr 1, 2013, 10:08:55 AM4/1/13
to
On Mon, 01 Apr 2013 13:18:07 +0100, Arfa Daily <arfa....@ntlworld.com>
It's not the logic that's slow, it's the control of the output voltage by
the field current that has an inherent lag.
the field current that has an inherent lag.
Duncan Wood
Apr 1, 2013, 10:11:04 AM4/1/13
to
On Mon, 01 Apr 2013 13:07:34 +0100, Arfa Daily <arfa....@ntlworld.com>
wrote:
>
>
But Varistors that can absorb 200J repeatedly are serious money, and
rarely necessary, jump starting with some load attached is far cheaper.
wrote:
>
>
rarely necessary, jump starting with some load attached is far cheaper.
Arfa Daily
Apr 1, 2013, 10:13:15 AM4/1/13
to
news:xn0igazy...@reader80.eternal-september.org...
They can certainly be hung across every IO pin on an ECU. They are readily
available as surface mount devices, and indeed, there are classes of them
made specifically for use in automotive products, which should tell us
something. Given that, for the purposes of board assembly, they can be
treated exactly the same as any other two contact surface mount device, I
fail to see why it would be impractical to protect each connection that goes
from the ECU to the outside world ?
Arfa
available as surface mount devices, and indeed, there are classes of them
made specifically for use in automotive products, which should tell us
something. Given that, for the purposes of board assembly, they can be
treated exactly the same as any other two contact surface mount device, I
fail to see why it would be impractical to protect each connection that goes
from the ECU to the outside world ?
Arfa
Arfa Daily
Apr 1, 2013, 10:14:47 AM4/1/13
to
news:xn0igb1j...@reader80.eternal-september.org...
I have to admit that I am having some difficulty picking the sense out of
that statement, particularly in relation to the current discussion ?
Arfa
that statement, particularly in relation to the current discussion ?
Arfa
Duncan Wood
Apr 1, 2013, 10:19:10 AM4/1/13
to
On Mon, 01 Apr 2013 15:14:47 +0100, Arfa Daily <arfa....@ntlworld.com>
wrote:
>
>
I don't understand the 2nd bit, but then I don't see how the starter puts
a spike back on the 12V rail, the reason it's input goes high is that it's
disconnected from the 12V rail. Unless you're doing somethig very strange
it won't be driven by the alternator. (Presumably jumping a dead car with
a car with a knackered battery may also be a bad idea if you don't follow
the instructions)
wrote:
>
>
a spike back on the 12V rail, the reason it's input goes high is that it's
disconnected from the 12V rail. Unless you're doing somethig very strange
it won't be driven by the alternator. (Presumably jumping a dead car with
a car with a knackered battery may also be a bad idea if you don't follow
the instructions)
Dave Plowman (News)
Apr 1, 2013, 10:59:41 AM4/1/13
to
In article <xn0igb1j...@reader80.eternal-september.org>,
--
*I never drink anything stronger than gin before breakfast *
steve robinson <st...@colevalleyinteriors.co.uk> wrote:
> A starter motor is isolated on the live side of the power supply by a
> soleniod or relay setup so any current spike dumps straight into the
> ground circuit
Not when it's turning. Try looking at the supply with a 'scope.
> A starter motor is isolated on the live side of the power supply by a
> soleniod or relay setup so any current spike dumps straight into the
> ground circuit
--
*I never drink anything stronger than gin before breakfast *
steve robinson
Apr 1, 2013, 11:04:18 AM4/1/13
to
not every wire comming out of the ecu carries +12 volts some carry 3
volts some carry 5 volts some carry dc some carry ac some are 0 volts
otheres can be -3 volts -5 volts -12 volts some wires are signal wires .
Some wires are even multifunction
Varistors are only of any use for voltage surges , no good at all for
inrush of current.
steve robinson
Apr 1, 2013, 11:17:13 AM4/1/13
to
Dave Plowman (News) wrote:
> In article <xn0igb1j...@reader80.eternal-september.org>,
> steve robinson <st...@colevalleyinteriors.co.uk> wrote:
> > A starter motor is isolated on the live side of the power supply by
> > a soleniod or relay setup so any current spike dumps straight into
> > the ground circuit
>
> Not when it's turning. Try looking at the supply with a 'scope.
Agreed but at that point its pulling the load itself once its started
> In article <xn0igb1j...@reader80.eternal-september.org>,
> steve robinson <st...@colevalleyinteriors.co.uk> wrote:
> > A starter motor is isolated on the live side of the power supply by
> > a soleniod or relay setup so any current spike dumps straight into
> > the ground circuit
>
> Not when it's turning. Try looking at the supply with a 'scope.
the car it disconnects from the flywheel and the load drops off .
When the key is realeased the unit is isolated again via the relay and
soleniod system
Dave Plowman (News)
Apr 1, 2013, 1:42:27 PM4/1/13
to
In article
<1521571230386516482.855614%steve%-mallo...@news.eternal-september.org>,
Did say from the start it requires decent design. Which I'd not expect on
a Jeep.
--
*I don't suffer from insanity, I enjoy every minute of it *
<1521571230386516482.855614%steve%-mallo...@news.eternal-september.org>,
a Jeep.
--
*I don't suffer from insanity, I enjoy every minute of it *
Chris Whelan
Apr 1, 2013, 2:07:10 PM4/1/13
to
On Mon, 01 Apr 2013 14:21:19 +0100, Dave Plowman (News) wrote:
[...]
> Have you not noticed that it's always only the ECU which is damaged by
> this scenario? Never any of the other multitude of electronics on a
> modern car? So just how is it not practical to protect it if needed?
If you were jumping a car with a flat battery, you wouldn't have too many
other items switched on. If other items did fail, it may not be noticed
until later.
[...]
> Have you not noticed that it's always only the ECU which is damaged by
> this scenario? Never any of the other multitude of electronics on a
> modern car? So just how is it not practical to protect it if needed?
other items switched on. If other items did fail, it may not be noticed
until later.
Tim+
Apr 1, 2013, 4:57:52 PM4/1/13
to
Tim
Duncan Wood
Apr 1, 2013, 7:19:49 PM4/1/13
to
not one of the cells has gone open circuit. Most of the time it's an ideal
heavy load, under almost all the circumstances it isn't then it won't
start the car on it;s own.
Dave Plowman (News)
Apr 1, 2013, 7:43:09 PM4/1/13
to
In article
<476623360386542754.998828...@news.eternal-september.org>,
If it was ok before it went flat and hasn't been flat for long, yes. But
if it has failed through one or more cells going high impedance or has got
sulphated, no.
--
*Why is it that doctors call what they do "practice"?
<476623360386542754.998828...@news.eternal-september.org>,
If it was ok before it went flat and hasn't been flat for long, yes. But
if it has failed through one or more cells going high impedance or has got
sulphated, no.
--
*Why is it that doctors call what they do "practice"?
Arfa Daily
Apr 1, 2013, 8:54:51 PM4/1/13
to
news:op.wuu78...@duncan-tosh.lan...
Yeah, I can see that there is likely to be some inherent lag with the
inductance of the field coils storing energy, but nearly half a second ?
Seems like a long time to me ...
Arfa
inductance of the field coils storing energy, but nearly half a second ?
Seems like a long time to me ...
Arfa
Mrcheerful
Apr 4, 2013, 8:46:22 AM4/4/13
to
(rather than absolutely dead)
Chris Whelan
Apr 4, 2013, 8:58:49 AM4/4/13
to
On Thu, 04 Apr 2013 13:46:22 +0100, Mrcheerful wrote:
[...]
> so really a bump start if possible is safer all round if the battery is
> low (rather than absolutely dead)
Absolutely. Unless it's a recent twin-battery Transit...
[...]
> so really a bump start if possible is safer all round if the battery is
> low (rather than absolutely dead)
David Taylor
Apr 4, 2013, 9:03:56 AM4/4/13
to
On 2013-04-04, Chris Whelan <cawh...@prejudicentlworld.com> wrote:
> On Thu, 04 Apr 2013 13:46:22 +0100, Mrcheerful wrote:
>
> [...]
>
>> so really a bump start if possible is safer all round if the battery is
>> low (rather than absolutely dead)
>
> Absolutely. Unless it's a recent twin-battery Transit...
I thought bump starting, like curiosity, kills cats?
> On Thu, 04 Apr 2013 13:46:22 +0100, Mrcheerful wrote:
>
> [...]
>
>> so really a bump start if possible is safer all round if the battery is
>> low (rather than absolutely dead)
>
> Absolutely. Unless it's a recent twin-battery Transit...
--
David Taylor
Dave Plowman (News)
Apr 4, 2013, 9:05:23 AM4/4/13
to
In article <AFe7t.349068$VO5.2...@fx20.fr7>,
totally dead are extremely remote.
--
*I didn't say it was your fault, I said I was blaming you.
Mrcheerful <g.odon...@yahoo.co.uk> wrote:
> The biggest inductive load on a car is the starter motor. Which
> > certainly does produce vast spikes when the current is removed. It
> > also takes rather more 'current' than the alternator produces - and
> > according to these articles it's 'high current spikes' that cause the
> > problem. And of course, all ignition systems operate on just this
> > principle. The primary device that prevents these spikes from doing
> > damage is the very low impedance battery - and the way things are
> > wired from it. It is already a very efficent surge suppressor.
> so really a bump start if possible is safer all round if the battery is
> low (rather than absolutely dead)
The chances of damaging anything with a jump start where the battery isn't
> The biggest inductive load on a car is the starter motor. Which
> > certainly does produce vast spikes when the current is removed. It
> > also takes rather more 'current' than the alternator produces - and
> > according to these articles it's 'high current spikes' that cause the
> > problem. And of course, all ignition systems operate on just this
> > principle. The primary device that prevents these spikes from doing
> > damage is the very low impedance battery - and the way things are
> > wired from it. It is already a very efficent surge suppressor.
> so really a bump start if possible is safer all round if the battery is
> low (rather than absolutely dead)
totally dead are extremely remote.
--
*I didn't say it was your fault, I said I was blaming you.
Chris Whelan
Apr 4, 2013, 9:44:48 AM4/4/13
to
On Thu, 04 Apr 2013 14:05:23 +0100, Dave Plowman (News) wrote:
[...]
[...]
> The chances of damaging anything with a jump start where the battery
> isn't totally dead are extremely remote.
Yep, and extremely expensive when it happens.
> isn't totally dead are extremely remote.
steve robinson
Apr 4, 2013, 9:46:43 AM4/4/13
to
Dave Plowman (News)
Apr 4, 2013, 10:05:03 AM4/4/13
to
In article <ktf7t.259518$eU7....@fx24.fr7>,
nothing, obviously. Or get it towed home. Or just buy a new car. ;-)
--
*Why were the Indians here first? They had reservations.*
Chris Whelan <cawh...@prejudicentlworld.com> wrote:
> On Thu, 04 Apr 2013 14:05:23 +0100, Dave Plowman (News) wrote:
> [...]
> > The chances of damaging anything with a jump start where the battery
> > isn't totally dead are extremely remote.
> Yep, and extremely expensive when it happens.
Ok - so just go out and buy a new battery on each occasion. That costs
> On Thu, 04 Apr 2013 14:05:23 +0100, Dave Plowman (News) wrote:
> [...]
> > The chances of damaging anything with a jump start where the battery
> > isn't totally dead are extremely remote.
> Yep, and extremely expensive when it happens.
nothing, obviously. Or get it towed home. Or just buy a new car. ;-)
--
*Why were the Indians here first? They had reservations.*
Dave Plowman (News)
Apr 4, 2013, 10:06:39 AM4/4/13
to
In article <slrnklquhs.tb...@webber.yadt.co.uk>,
That would require the engine management to inject fuel without it
sparking. Most won't allow that.
--
*If a mute swears, does his mother wash his hands with soap?
sparking. Most won't allow that.
--
*If a mute swears, does his mother wash his hands with soap?
Duncan Wood
Apr 4, 2013, 11:19:27 AM4/4/13
to
On Thu, 04 Apr 2013 15:05:03 +0100, Dave Plowman (News)
<da...@davenoise.co.uk> wrote:
> In article <ktf7t.259518$eU7....@fx24.fr7>,
> Chris Whelan <cawh...@prejudicentlworld.com> wrote:
>> On Thu, 04 Apr 2013 14:05:23 +0100, Dave Plowman (News) wrote:
>
>> [...]
>
>> > The chances of damaging anything with a jump start where the battery
>> > isn't totally dead are extremely remote.
>
>> Yep, and extremely expensive when it happens.
>
> Ok - so just go out and buy a new battery on each occasion. That costs
> nothing, obviously. Or get it towed home. Or just buy a new car. ;-)
>
Or follow the instructions that came with the car.
<da...@davenoise.co.uk> wrote:
> In article <ktf7t.259518$eU7....@fx24.fr7>,
> Chris Whelan <cawh...@prejudicentlworld.com> wrote:
>> On Thu, 04 Apr 2013 14:05:23 +0100, Dave Plowman (News) wrote:
>
>> [...]
>
>> > The chances of damaging anything with a jump start where the battery
>> > isn't totally dead are extremely remote.
>
>> Yep, and extremely expensive when it happens.
>
> Ok - so just go out and buy a new battery on each occasion. That costs
> nothing, obviously. Or get it towed home. Or just buy a new car. ;-)
>
Chris Whelan
Apr 4, 2013, 11:50:59 AM4/4/13
to
loads on the car with the flat battery before disconnection; it's not
exactly difficult.
Chris Whelan
Apr 4, 2013, 11:52:27 AM4/4/13
to
On Thu, 04 Apr 2013 15:05:03 +0100, Dave Plowman (News) wrote:
> In article <ktf7t.259518$eU7....@fx24.fr7>,
> Chris Whelan <cawh...@prejudicentlworld.com> wrote:
>> On Thu, 04 Apr 2013 14:05:23 +0100, Dave Plowman (News) wrote:
>
>> [...]
>
>> > The chances of damaging anything with a jump start where the battery
>> > isn't totally dead are extremely remote.
>
>> Yep, and extremely expensive when it happens.
>
> Ok - so just go out and buy a new battery on each occasion. That costs
> nothing, obviously. Or get it towed home. Or just buy a new car. ;-)
The person I know of that killed the ECU on his T4 would have happily
> In article <ktf7t.259518$eU7....@fx24.fr7>,
> Chris Whelan <cawh...@prejudicentlworld.com> wrote:
>> On Thu, 04 Apr 2013 14:05:23 +0100, Dave Plowman (News) wrote:
>
>> [...]
>
>> > The chances of damaging anything with a jump start where the battery
>> > isn't totally dead are extremely remote.
>
>> Yep, and extremely expensive when it happens.
>
> Ok - so just go out and buy a new battery on each occasion. That costs
> nothing, obviously. Or get it towed home. Or just buy a new car. ;-)
paid £100 for a new battery rather than the £600 it cost him to have it
towed/diagnosed/repaired.
Grimly Curmudgeon
Apr 24, 2013, 10:51:00 PM4/24/13
to
On Fri, 29 Mar 2013 13:58:18 +0000 (GMT), "Dave Plowman (News)"
<da...@davenoise.co.uk> wrote:
>Have you ever known a battery to explode through gassing? Except when on
>charge in a confined area? Hydrogen is one of the lightest of gasses, so
>will not hang around. Generally, when a jump start is attempted, it's in
>the open air.
I certainly know of one that blew up in the works foreman's face when
he was jumpstarting it - with a welder.
Silly sod was lucky not to lose an eye or two.
<da...@davenoise.co.uk> wrote:
>Have you ever known a battery to explode through gassing? Except when on
>charge in a confined area? Hydrogen is one of the lightest of gasses, so
>will not hang around. Generally, when a jump start is attempted, it's in
>the open air.
I certainly know of one that blew up in the works foreman's face when
he was jumpstarting it - with a welder.
Silly sod was lucky not to lose an eye or two.
newshound
Apr 25, 2013, 3:57:32 PM4/25/13
to
On 04/04/2013 13:46, Mrcheerful wrote:
>
> so really a bump start if possible is safer all round if the battery is low
> (rather than absolutely dead)
>
>
For a long time now I have been carrying a tow-rope instead of a set of
>
> so really a bump start if possible is safer all round if the battery is low
> (rather than absolutely dead)
>
>
jump leads, mainly for tow starting. Avoids all the hassle of not quite
adequate connections or having to move cars into odd layouts because
domestic jump leads are shorter and less grippy than proper garage ones.
And, even if the car won't start you can still move it!
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